He's already an ML quality hitter at 18 (not great, but can hit well enough, and will only develop from there, regardless of what his true projections are). I know a lot of people that would have no qualms about playing him at 2B... I am starting to lean that way as well (to the POV that 2B defense is not all that important... and a 75 R 60 Glove guy is fine there). I don't see a problem with high 80's durability and high 60's to low 70's health. I would place little value on his speed with that baserunning, though.
In short, I would have no problem spending 15-20 mill on that guy in any of my worlds.

To me he looks like a solid COF, who might end up with a .400 OBP and .850 OPS. I have a catcher (http://whatifsports.com/HBD/Pages/Popups/PlayerProfile.aspx?pid=2591925) who has somewhat similar numbers (flip BE and CON) and puts up good stats as an everyday player and monster stats as a platoon. And he's as slow as the Mexican tax system...add speed to that and I think you have a really solid player. Your prospect's health line is not that bad, though I would bet his STAM tops out around 75-80. I would have no qualms about spending 15-20mil on him.

Spend the money. That guy will be a great #1 or #2 hitter and would also be a potential gold glover in LF. You could on the other hand play him everyday but move him around the diamond to give other guys rest. I do this on one of my teams for a guy in a similar situation defensively who owns a monster bat and it has worked out wonderfully.

You have a 38 M prospect budget. That means, at best, you've transferred 18 M, meaning you've f'd away 18M transferring that amount. Goodbye 10% of this seasons total budget.

Now, you're thinking about f'ing away another 10%...for a total of 20%,,,on a dude, that is a negative play fielder anywhere but the COF, and if he does get .850 OPS, most of it is coming one base at a time.

Hart has similar splits, lower contact, more power, is somewhat slower, but is a better baserunner. I suspect that the contact/power differences will largely cancel each other out in terms of value.

Assuming that your guy develops well, I'd say that slash stats of 320/400/450 are not unreasonable. His speed will largely offset his less than optimal baserunning to the extent that his basestealing will probably border on the irrelevant with a 65-70% success rate. He may also surprise you with 20-25 HRs a year - his high contact and splits means that he's going to be putting a lot of hard hit balls in play. Even without a lot of raw power, some of them are going to land on the other side of the fence.